There has been an attempt to recycle hygiene products such as used disposable paper diapers, etc. In order to recycle used hygiene products, normally, the used hygiene products are decomposed in water, and components of the hygiene products are separated and recovered. However, the polymer absorbent material (hereinbelow, also referred to as “SAP”) included in the hygiene products increases the mass thereof by absorbing moisture and loses liquidity due to transforming into a gel state, whereby lowers the treating capacity of the treatment apparatus.
Accordingly, Japanese Unexamined Patent Publication No. 2014-217835 proposed a method of decomposing the SAP in the used paper diaper, making the SAP dissolvable and removing the SAP by immersing the used paper diaper in an acidic ozone water with pH of 3 or lower.